have purchased several $10-$50 bikes and parted them or moved them on, but the lowest level of them that I have actually ridden was a '87 Schwinn World, I gifted it to my nephew even though it was my first ride in 1987 - nothing special about those, hi ten frame, the wheels may have even been steel instead of alumum, etc but I had no idea in '87 and put thousands of miles on it
of my current bikes, this '81 LeTour Frame is prob the lowest level - 1020 Carbon steel, but also one of my nicest...
'81 LeTour New Old Stock Frame, with a mismatched chrome fork